Process for making polyvalent metallic salts of half esters of phthalic acid



Patented Oct. 28, 1930 ."UNITED STATES PATENT OFFICE- WEI-1AM J. BANNISTER, OF T'EIRBE HAUTE, INDIANA, ASSIGNOR TO COMMERCIAL SOLV'ENTS CORPORATION, OF TERRE HAUTE, INDIANA, A CORPORATION OF MARY- LAND PROCESS FOR MAKING POLYVALENT METALLIC SALTS OF HALF OF .PHTHALIO ACID Io Drawing. Application filed June 13,

My invention relates to an improved method of preparing polyvalent metallic salts of half esters of phthalic acid. More particu larly, my invention relates to a method of 5 preparing compounds of this type which are soluble in solvents immiscible in water.

' In Canadian Patent 260,927 of May 8, 1926, Bruce K. Brown and Charles Begin have disclosed the use of certain metal alkyl resins as components of nitrocellulose lacquer adapted to partly or completely replace varnish gums. United States Serial Nos. 253,210. and 253,211, filed February 9, 1928, by C. W. Simms, W. J, Bannister and L. C. Swallen,

describe the use of these materials for the purpose of facilitating the grinding of pigments. They are also useful or various-other pur oses. a

T ese metal alkyl resins are more properly described as pol valent metallic salts of alkyl half esters o phthalic acid. Their structure may be expressed by the following type formula: 7

in which M represents a divalent metal, and

- R an alkyl group such as methyl, ethyl, pro- I pyl, butyl, etc., or an aryl group such as phenyl, tolyl, benzyl, or cinnamyl. In place of M, polyvalent metals such' as zinc, copper,

- lead, iron, aluminium, manganese, nickel, co-

balt, etc., may be substituted.

Altho there are naturally some exceptions to the general statement, the polyvalent metallic salts of half esters of phthalic acid may be generally characterized as solid, stable, neutral, resin-like substances, insoluble 40 in water, soluble in organic solvents, and exerting a solvent action on nitrocellulose. The

zinc and iron butyl phthalates are plastic solids similar to certain resins in some'of their physical properties, the zinc compound being colorless and the'iron, reddish-brown. The

1928. Serial No. 285,225.

corresponding copper compound is a dry powder, bluish-green in color.

In the past it has been the custom to prepare polyvalent'metallic salts of half esters by neutralizing the monobutyl phthalate with sodium hydroxide in aqueous solution. An aqueous solution of some soluble zinc salt was then added in equivalent proportions, with rapid agitation. 1 The zinc butyl phthalate obtained in this manner formed as a very sticky semi-liquid which slowly settled to the bottom of the reaction vessel. It was later-dissolved in some suitable solvent and purified by dehydration and filtration. Dehydration was accomplished by choosing a solvent forming a constant boiling mixture, and distilling. The yields thus obtained were low due to inclusion of'the'soluble zinc compound and also of sodium butyl phthalate solution by the pasty zinc butylphthalate. There was also an appreciable amount lost thru solution in the water. In general, many difliculties were experienced in thismethod of preparation due to the sticky nature of the compound.

I have now discovered a method of effectin'g the preparation of these compounds in the presence of waterrim'miscible solvents which gives greatly improved results over methods previously. employed. By my new method, it is possible, if desired, to omit one step in the procedure customarily employed.

The following examples are cited as illustrative of my'new process.

Ewample I 1630 grams of phthalic anhydride is added in several portions to a mixture of 825 grams of butyl alcohol and 1000 grams of toluol, maintained at a temperature of approximately 100 C. After a homogeneous solution results, the heating is continued at this temperature for approximately 1 hour. This operation gives monobutyl phthalate. After cooling, a 10% sodium hydroxide solution, made up by dissolving 450 grams of 95% sodium hydroxide in 3600 c. c. of water, is added to the monobutyl phthalate-toluol solution until the latter is just alkaline to phenolphthalein. The temperature should be kept below -70 (1., and preferably below 50 (1, and the mass well agitated while the "sodium hydroxide is being added. A solution of 1600 grams of zinc sulphate (ZnSO .7H O) in 2 liters of water is next added under good agitation and the mixture allowed to settle in a separating funnel. .In this manner, zinc butyl phthalate is obtained from the previously formed sodium butyl phthalate. After separation of the oil and water layers, the former is placed in a flask and distillation under reduced pressure (100 mm. or less) started. This is continued until no more water comes over with the toluol. If there is a large amount of water present, more toluol may be added to the flask. It is important that during this operation the temperature of the liquid in the flask should not exceed approximately 80 C. After cooling, any residual zinc sulphate or sodium sulphate present in the compound may be removed by filtration.

desired, to om1t in my new process the step involving the preparation of the mono-- valent alkyl phthalate (e. g., sodium butyl phthalate). This point is illustrated in Example II described below.

Emample H addition of the zinc oxide, since the presence of a small amount of water has been foun to=expedite the reaction. After all of th zinc oxide has been added, agitation As previously pointed out, it is possible, I

greater than 0.1% '(calculated as phthalic acld) ap roximately 1 lb. more of zinc oxide is added and the reacting mixture maintained at 7 080 C. for an additional halfhour. When the acidity is found to be reduced sufficiently, the reaction kettle is closed and the reaction mixture heated for 1 hour under 25 vacuum at C. When all of the water present has been removed, the reaction product is allowed to cool. After standing for 3 to 6 days it is filtered to remove unused zinc oxide, zinc phthalate, etc. Petroleum hydrocarbon or other solventi may be removed by distillation, if de sire v If desired, a solvent boiling below 100 C. may be employed in place of one boiling above 100 0., asspecified above. If a low boiling solvent is employed, however, it is necessary to conduct the reaction in a closed. vessel to prevent the loss of the solvent. In an alternative method of carr 'ng out my new process, somewhat lower boiling solvents may be employed. In this case the addition of the solvent material is omitted until after the first step, e. g., the preparation of monobutyl phthalate, has been completed. As soon as this part of the reaction is over the solvent may be added and the operation completed as previously described, the desired advantages being obtained by the presence of the solvent during the latter steps.

It is distinctly understood that the examples describe above are cited only as illustrations ofacceptable variations in my new method of preparing polyvalent metallic salts of half esters of phthalic'acid and that many other similar products ma be obtained in the same manner merely y suitably varying the constituents entering into 1 the reaction. For example, in'place of butyl alcohol, I may employ any other alcohol such as methyl, ethyl, propyl, amyl, benzl, cinnamyl, etc. Instead of a Zmc com ound,

I may use a suitable compound of suc polyvalent metals as iron, lead, copper, nickel,

cobalt, aluminium, etc. As the solvent required in the process, I may employ any material of suitable boiling point which is a I,

good solvent for the polyvalent metallic salt of the half ester of phthalic acid being formed, provided it is immiscible with water and does not readily enter into reaction with any of the other materials present under .the conditions of the reactions. The character of the solvent to be employed depends also upon whether or not it is desired to separate it from the final product being prepared. Examples of suitable solvents for 1,779,ese

use in'my processes are: coal tar hydrocarbons, petroleum hydrocarbons, and if it is not desired to separate the resulting compound, such solvents as dibutyl phthalate and butyl stearate.

As pointed out above, it has formerly been the custom to prepare polyvalent metallic salts of half esters of phthalic acid by carrying out the various steps of the process in the presence of water and eventually attempting the recovery of the finished product by means of various solvents. This method of procedure led to many difiiculties and gave poor yields. By my new process ofeflecting the formation of these materials in the presence of water-immiscible solvents into which they pass insolution as formed, the diificulties formerly experienced are entirely overcome and at the same. time better yields and a better grade of products are obtained.

Now having described my invention, what I claim as new and novel is:

1. The process of preparing pol alent metallic salts of half esters of phtha ic acid which comprises effecting the reaction in the presence of solvents immiscible in waterand not entering appreciably into reaction with any of the other materlals present.

2. The process of preparing polyvalent metallic salts of half esters of phthalic acid which comprises reacting alcohols and phthalic'anhydride in the presence of solvents immiscible in water and not entering appreciably into reaction with any of the materials present, neutralizing the resulting product with alkalis, adding aqueous solutions of salts of polyvalent metals, and finally recovering the said polyvalent salt of half esters of phthalic acid from the resulting water-immiscible solvent layer.

3. The process of preparing polyvalent metallic salts of half esters of phthalic acid which comprises reactingphenols and phthalic anhydride in the presence of solvents immiscible in water and not entering appreciably into reaction with any of the materials present, neutralizing the resulting product with alkalis, adding aqueous solutions of salts of polyvalent metals, and finall recovering the said polyvalent salts of ha f esters of phthalic acid from the resulting waterimmiscible solvent layer.

4. The process of preparing polyvalent metallic salts of half esters of phthalic acid which comprises reacting alcohols and phthalic anhydride, neutralizing the resultmg product with alkalis, adding solvents immiscible in water and not entering appreciably into reaction with any of the materials present, adding aqueous solutions of salts'of polyvalent metals, and finally recovering the said polyvalent salts of half esters of phthalic acid from the resulting water-immiscible solvent layer.

5. The process of preparing polyvalent metallic salts of butyl half esters of phthalic acid which comprises reacting butyl alcohol and phthalic anhydride in the presence of solvents immiscible in water and not entering appreciably into reaction with any of the materials present, neutralizing the resulting product with alkalis, adding aqueous solutions of salts of-polyvalent metals, and finally recovering the said polyvalent salts of butyl half esters of phthalic acid from the resulting water-immiscible solvent layer.

' 6. The process, of preparing polyvalent metallic salts of butyl half esters of phthalic acid which comprises reacting butyl alcohol and phthalic anhydride, neutralizing the resulting product with alkalis, adding solvents immiscible in water and not entering appreciably into reaction with any of the materials present, adding aqueous solutions of salts of polyvalent metals, and finally recovering the said polyvalent salts of butyl half esters of phthalic acid from the resulting water-immiscible solvent. layer.

7. The process of preparing polyvalent metallic salts of half esters of phthalic acid which comprises reacting ali hatic alcohols and-phthalic anhydride in t e presence of coal tar hydrocarbons, neutralizing the resulting product with alkalis, adding aqueous solutions of salts of polyvalent metals, and

finally recovering the said polyvalent salts of half esters of phthalic acid from the resulting coal tar hydrocarbon layer.

8. The process of preparing polyvalent metallic saltsof alkyl half esters of phthalic acid which comprises reacting aliphatic alcohols a-nd phthalic anhydride in the presence of toluol, neutralizing the resulting roduct with alkalis, adding aqueous solutions. of salts of polyvalent metals, and finally recovering the polyvalent salts of alky esters of phthalic acid from. the resulting toluol layer.

' 9. The process of pre aring polyvalent metallic salts of alkyl halfsters of phthalic acid which comprises reacting ali hatic alcohols and phthalic anhydride in t e presence of petroleum hydrocarbons, neutralizing the resulting product 1 with alkalis, adding 1 half aqueous solutions of salts of polyvalent H metals, and finally recovering the said polyvalent salts of alkyl half esters of phthalic acid from the resulting petroleum hydrocarbon layer.

10. The process of preparing the zinc salt of the butyl half ester of phthalic acid which comprises reacting butyl alcohol and phthalic anhydride, neutralizing the resulting prodnot with alkalis, adding solvents immiscible in water and not entering appreciably into reaction with any of the materials present, adding an aqueous solution of a zinc salt and finally recovering the said zinc salt of the butyl half ester of phthalic acid from the resulting water-immiscible solvent layer.

11. The process of preparin the zinc salt of the butyl half ester of phtha ic acid which comprises reacting butyl alcohol and phthalic acid in the presence of toluol, neutralizing the resulting product with alkalis, adding an aqueous solution of a zinc salt, and finally recovering the said zinc salt of the butyl half ester of phthalic acid from the resulting toluol layer.

In testimon whereof I afix my si ature.

WiLLIAM J. BANNI TER. 

